CD79A and arthritic joint disease: EULAR/PRINTO/PRES criteria for diagnosis of IgAV include purpura or petechiae and one of the following four criteria (abdominal pain, arthritis/arthralgia, renal involvement, and leukocytoclastic vasculitis with predominant IgA deposits or proliferative glomerulonephritis with predominant IgA deposits) [10].